Window assemblies have historically been fabricated with a structural base frame, a sash frame that holds one or more glass panes, an exterior accessory frame, and various trim pieces. The base frame is the portion of the window assembly which is attached to the structure of the building. The sash frame is the portion of the window assembly which holds the window pane and fits within the base frame. The exterior accessory frame is the exterior portion of the window assembly that defines the exterior aesthetic appearance of the window assembly and provides for weather protection. Some window assemblies require that the base frame be uniquely designed to match a particular exterior accessory frame. Some window assemblies require that the exterior accessory frame be connected to the building structure and to the base frame. Improvements are desired.